钒钛磁铁精矿内配煤球团还原分形论动力学研究

Fractal Kinetics Study on Reduction of Vanadic-Titanomagnetite-Coal Mixed Pellet

基于分形理论建立了矿煤球团还原动力学新模型,通过钒钛磁铁精矿内配煤球团加热还原试验,探讨钒钛磁铁精矿内配煤球团分形还原机理.实验结果发现,钒钛磁铁精矿表面分维为2.2686;实验温度范围（960～1200℃）内,球团还原时间短于23 min时,其表观速率常数与温度之间关系为k1=624.843exp（-1.5324×10^4/T）min-1,活化能为127.40kJ·mol-1;球团还原时间超过28 min后,其表观速率常数与温度之间关系为k2=0.035×exp（-0.5329×10^4/T） min-1,活化能为44.31kJ·mol-1.结果表明,球团还原初期主要受碳气化反应限制,后期主要受内扩散限制.

A fractal kinetics model was built and some experiments were carried out so as to study the fractal reduction kinetics of vanadic-titanomagnetite-coal mixed pellet. The experiments show that the fractal dimension of the concentrate is 2. 2686. The relations between the reduction velocity constant and temperature （960-1200℃） are kl 624. 843exp（-1. 5324×10^4/T） min-1 in about 23 rain and k2 =0. 035exp（-0. 5329 ×10^4/T） rain-1 after about 28 min, respectively. And the activation energy of the pellet is 127. 40 kJ · mo1-1 in about 23 rain and 44. 31 kJ·mo1-1 after about 28 rain, respectively. It shows that the limiting unit of the reduction of the pellet is the carbon gasification reaction in earlier stage and the diffusion in later stagein, respectively.